Expendable frangible connector



June 9, 1964 J. M. PERKINS ETAL 3,136,842

EXPENDABLE FRANGIBLE CONNECTOR Filed June 12, 1961 28 INVENTORS JAMES M. PERKINS PAUL F. GRAF BY FRANK R. BRAUN ATTORNEY United States Patent O 3,136,842 EXPENDABLE FRANGIBLE CONNECTOR James M. Perkins and Paul F. Graf, Oxnard, and Frank R. Braun, Ventura, Califi, assignors to the United States of America as represented by the Secretary of the Navy Filed June 12, 1961, Ser. No. 116,628 5 Claims. (Cl. 1 74-88) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to electrical connectors, and

. more specifically to an electrical connector having a fran- .gible electrical connection that will separate with a minimumresistant force.

' Thisinvention is particularly adapted for use in umbilical connectors that electrically join a missile with the .launching structure, which may be an aircraft or a fixed launcher.

As. would be expected, many difierent types of umbilical connectors have been proposed, and for the most parts such connectors employ metal pins slidably fitting in female sockets. Although pin-ty e umbilical connectors have been successfully employed in many different types of installations, they present several disadvantages which the instant invention overcomes. One disadvantage of pin-type umbilical connectors is the difiiculty of protection against moisture which may cause an electrical short. Probably more critical is that inmissiles launched in a forward direction, the connector halves must be first ejected apart which necessitiates the use of springs, etc. .which mechanisms present additional disadvantages. careful alignment between the connector halves, other- Pin-type connectors also require 3,136,842 Patented June 9, 196 4 Other objects and many of the attendant advantages of this invention will. be readily appreciated as the same becomes. better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein the sole figure is a longitudinal view of an assembled connector, partially in section to show construction details.

Referring to the drawing where like reference numerals designate similar parts, there is shownin the single figure a novel electrical connector 10 illustrated as an umbilical connection for a missile 11, and comprises a pair of counterpart separable halves 12 and 14. Connector half 12 is adapted to be electrically connected by conductors 16 and a conventional connector 18 to a launching platform (not shown) which may be an aircraft or a fixed structure, being secured thereto by four hooks 20 adapted to engage posts 22 mounted on the connector half. The other connector half 14 is supported on the missile frame 24 by mounting ring 26 and electrically connected to the missile components (not shown) by conductors 28. By such a connection electrical energy can be transmitted between the launcher control station and the missile components for various types of prelaunch operations until the time of launch when the connector halves are separated to disconnect the electrical circuitry.

Connector halves 12 and 14 comprise bodies 30 and 32 made of insulating material, such as nylon, having facing surfaces 34 and 36, respectively, adapted to be abutted in the assembled configuration. Bodies 30 and'32 can be constructed of, or cast as blocks having configurations that can be varied according to the shape of the opening 38 available in the missile skin 40 for this purpose. Abutting surfaces 34 and 36 of the connector halves can be fiat to lie in a shear plane 42 tangential to missile skin 40,. or the abutting surfaces may be concave-convex to form a curved shear surface to conmay of holes are drilled through both connector halves transverse to the shear surfaces and filled with a paste formed of conductive metal particles in a suitable binder which composition hardens to form a frangible material.

While the conductive paste is still soft, the bared ends of the conductors are inserted therein until the paste hardens with the bared ends securely fixed in position. Upon hardening, the paste material becomes highly conductive and readily frangible and the connector halves are easily separated by a predetermined tensile force, shear force, or'any combination of such forces.

The absence of metal pins and receptacles for electrical contact, eliminates friction which is particularly severe at low temperatures in which environment such umbilical connectors must function. The connector assembly may be cast or molded of a suitable nonconductive material that is completely waterproof. The shear surfaces ofthe missile connector half can be made flush with the missile body avoiding aerodynamic drag, and the connector halves need not be separated in only one direction.

A principal object of this invention is to provide a separable connector having increased reliability.

Another object is to provide a connector which eliminates the need for mating connector pins and sockets and ejection mechanisms for such parts, and one which enables separation of the mating parts with a minimum of friction.

the respective abutting surfaces, one aperture for each conductor to be electrically connected. During fabrication, each aperture is completely filled with a paste-like conductive material 46 and while the material is still soft the bared end 48 of the corresponding conductor is inserted therein until the material hardens to anchor the bared end firmly therein and form a good electrical joint. The insulated end of both sets of conductors 16 and 18 may be anchored to their respective connector bodies by a disc 49 made of potting compound.

One suitable conductive material 46 that has been used comprises a compound of 5 gm. of epoxy, 1 gm. hardener, and 27 gm. silver flake, which mixture will set and harden in about six hours. When hardened the conductive paste forms rods, or pins, that are frangible and can be readily parted by a force that may be in shear or tension or any combination thereof in a manner to be described.

Connector bodies 30 and 32 are secured together at their abutting surfaces by any readily separable means, preferably by an adhesive 50, such as one having a silicone rubber base. The type and formulation of adhesive 50 is dependent upon the area of the abutting surfaces, the desired separation force involved in the launch, and the missile operating environment. In one air-to-air missile launch, the adhesive was designed to permit separation of the connector halves by a 40 pound tensile force,

the remaining surface: body 32 being smooth and free of any large recesses or protuberances that might create a drag. It'is possible that the conductive paste pins could beutilized as the means for securing together the cone nector bodies.

One of'the advantages of the invention device is the.

simpleand inexpensivev construction that is possible with such an expendable connector. As an example, one.

method of fabricating the conector is to first'adhesively secure t'ogether'connector bodie s 30 and 32'with posts 22 and mounting ring 26' previously molded therein, making sure that the adhesive completely covers the entire 'abutting surfaces. Apertures 44 are then drilled through the assembled connector bodies and the adhesive layer, and the apertures thoroughly filled with conductive paste 46. The exposed 'sufaces of the connector bodies are 1 then cleaned, such as by sandblasting, of any conductive 7 verse to saidabutting surfaces, one opening for "each electrical conductor to be joined together, said openings being filled with an electrically conductive paste-like fnecting. a corresponding pair of electrical conductors, said connector halves having body portions made of in- 'sulating material with surfaces in 'abuttingrelation, severable means for securing together said body portions, said' body-portionscontaining atleast one, pair of aligned paste to prevent any accidental electrical jshort between] adjacent conductive paste-filled apertures. The ends of conductors 16 and 28 are then-stripped and the bared ends, i.e. A" in length, inserted in the still soft conductive paste. To maintain the assembled position of the conductors, a potting compound is poured around the frangible material having electrical continuity,- saidl'pair of conductors being electrically connectedto said con- 'ducti've material, whereby application of apre dtermined i force on one of said connector halves after the conductive.

'material hashardenedwill severl said frangible material 1 along the abutting surfaces ,to separatesaid connector halves. 1

2..An expendable electrical. separableconnector assem bly comprising a pairof counterpart halvesior'conopenings extending therethrough transverse to .said' abut ting surfaces," one opening for each electrical'conductor Ito be joined together, said openings being filled with I an. electrically conductive paste-likefrangible material,

ends of the conductors and allowed to harden, providing a moisture proof connector assembly.

In operation, the assembled connector halves are installed on the missile, with the abutting surfaces lying flush withthe surface of the missile skin, being the shear surface. The free ends of conductors 16.v and 28 ar'e. con

nected to the launching platform.andrnissilep'components,

respectively. The conductors are flexible to absorb'any Upon launching of the missile, the application of the separation force along the shear' surface causes adhesive 50' to part,.simulta.ueously snapshock due to vibration.

ping off the plurality of frangible pins of conductive material along the shear surface freeing the connector halves.

The shear surface of the missile connector half Sis relatively smooth and free of protuberances or recesses.

The novel connector of this invention provides a I 7 molded assembly which is completely waterproof, The connector'assembly is simpler than existing ,connectors because machining is eliminated,. and the'use of an ex pendable connector eliminates the tolerances normally said pair of conductors being electrically" connected to" said conductive 'rnate'rial to provide electrical continuity a between the" conductors {through saidsfrangiblematerial,

whereby applicationof a predcterinined'force pn one off said connector halves will separatesaid connector halves' j afterthe conductive material hasfhardened and sever the frangible material along the abutting surfaces.

3. The connector of claim 2 wherein said severable means is an adhesive.

4 The connectorofclaim 2 where, infsaid electrically I conductive frangible material isja plastic binder with electrically conductivernetalparticles suspended therein. 3 5. An expendable umbilical connector assembly comprising a pair of counterpart 'halves for connecting. a;

corresponding pair of electrical; conductors, said con- I nector halves having body portions made of insulatingmaterial with surfaces in abutting relation, adhesive means for securing said body portions in abutting relation and severable by apredetermined force,.saidbody portions containing apair' of aligned openings foreach required for nonexpendable connectors. The absence of metal pins and female receptacles for the electrical contact eliminates friction that is particularly severe at low-. temperature operations. The connector halves separate v along the shear surface, which may be alonga plane or curved surface conforming to themissile skin, upon the application of theseparation force which may in torsion,

shear, or' a combination thereof. It is apparent that separation 'of theconnector along a shear plane.simplifies embedded in said conductive material atfopposite ends of the openings to provide electrical continuity between} pair of conductors, said openings extending completely I through the body portions transverse to said abutting sur faces, said openings filled with an electrically conductive frangible material, bared ends of said pair of conductors the conductors through said conductivematerial, means for potting the ends ofthe conductorsadjacent the hated 5 ends to the respective connectorbodies" for providing a sealed assembly, whereby application of a predetermined,

forceon onejof saidconnctor'halves will separate the the construction in that the need fora means for ejecting I the old pin and socket connector is eliminated.

Obviously many modifications and variations of the 7 present invention are possible in thelightof the above teachings. It is, therefore, tobe understood that within the scope of the appended claimsthe invention may be I practiced otherwise than as specifically described.

We claim:

1. An expendable electrical separable connectonassembly comprising a pair of counterpart halves for connecting a corresponding pair of electrical conductors, said connector halves having body portions with surfaces in abutting relation, said bodyportionscontaining at least one pair of aligned openings extending therethrough transconnector bodies along a shear surface created by the adhesive .and sever thejfragible material to break the a 7 electrical connection.

References Cited in the file of this patent UNITED; STATES PATENTS; V

Gregoire Apr. 30,;1962 

1. AN EXPENDABLE ELECTRICAL SEPARABLE CONNECTOR ASSEMBLY COMPRISING A PAIR OF COUNTERPART HALVES FOR CONNECTING A CORRESPONDING PAIR OF ELECTRICAL CONDUCTORS, SAID CONNECTOR HALVES HAVING BODY PORTIONS WITH SURFACES IN ABUTTING RELATION, SAID BODY PORTIONS CONTAINING AT LEAST ONE PAIR OF ALIGNED OPENINGS EXTENDING THERETHROUGH TRANSVERSE TO SAID ABUTTING SURFACES, ONE OPENING FOR EACH ELECTRICAL CONDUCTOR TO BE JOINED TOGETHER, SAID OPENINGS BEING FILLED WITH AN ELECTRICALLY CONDUCTIVE PASTE-LIKE FRANGIBLE MATERIAL HAVING ELECTRICAL CONTINUITY, SAID PAIR OF CONDUCTORS BEING ELECTRICALLY CONNECTED TO SAID CONDUCTIVE MATERIAL, WHEREBY APPLICATION OF A PREDTERMINED FORCE ON ONE OF SAID CONNECTOR HALVES AFTER THE CONDUCTIVE MATERIAL HAS HARDENED WILL SEVER SAID FRANGIBLE MATERIAL 